In connection with the care and treatment of wound it is preferable that the selection and the design of a wound dressing focus on the specific requirement of the particular wound itself. The term wound is meant to include burns, pressure sores, punctures, ulcers and the like. A critical aspect of wound care is consideration of the requirements of the epithelium i.e. that area of new cell growth directly peripheral to the wound which is formed during the healing process so that healing is facilitated. Another consideration in wound treatment albeit of a somewhat lesser concern are the needs of the surrounding unwounded skin.
Since it is recognized that healing of the wound occurs in the epithelium by cell growth from the periphery inward, care is taken not to unnecessarily damage or irritate this new area of growth. Frequently, with prior art dressings, problems can occur during dressing changes particularly where the dressing adheres to the epithelium or where the granulation tissue and new cell growth becomes intertwined within the matrix of the dressing. In both instances, there is a risk that removal of the dressing will damage the sensitive tissue thereby causing a regression in progress of wound healing. Another concern in the selection of wound dressing is to provide a dressing that maintains a moist environment and prevents scab formation.
At least a portion of the area of the skin around the wound that has not been damaged by the wound is in contact with the wound dressing. For example, a significant portion of the surrounding skin may be covered for extended periods with the adhesive or a wrap which secures the dressing in position. The unwounded skin may be irritated by the dressing. This is particularly a problem with ulcers specifically leg ulcers where the surrounding skin can easily become sensitized by strong medicaments and such wounds are frequently accompanied with flaking, and/or scaling of the surrounding tissues or eczema.
Another factor in wound care is the frequency of dressing changes. The above are all considerations in the timing of dressing change. In addition, it is desirable to change dressing more frequently where the wound is emitting a large volume of exudate. Thus, considering the various types of wound, the numerous dressings that are available, and the various stages of healing, there is a need for a dressing that aids in monitoring the healing of the wound.
In the area of leg ulcers one type of treatment presently used comprises the application of gauze to the ulcer and the utilization of a compression wrap to secure the gauze to the ulcer. Since the gauze quickly becomes saturated, frequent changes are necessary and damage to the epithelium and surrounding skin may occur. If the gauze is left on for too long a period, the exudate which contains proteolytic enzymes can begin to digest the patient's surrounding skin.
A second type of treatment is the Unna's Boot (commercially available from Biersdorf, Inc.) which comprises a zinc paste-containing bandage wrapped around the patient's leg from above the toes to below the knee. Other Unna's Boot/zinc impregnated treatments are available from Miles and Graham Field. This dressing is typically left in place for a week at a time and absorbent pads must be applied to the outside of the dressing in the area of the ulcer to absorb excess exudate. Seepage of exudate throughout the wrap is common, however, and damage to the skin and epithelium is inevitable.
Another type of dressing is disclosed in U.S. Pat. No. 5,106,362 to Gilman. This dressing is provided with a base sheet for contacting the skin of the patient. The base sheet has an opening for placement over the wound. The dressing has a vent for providing controlled leakage of fluid along a path from the wound through the opening of the base sheet. The vent is designed to provide control over wound leakage along a "tortuous path" from the wound through the opening of the base sheet.
A modification of the dressing of U.S. Pat. No. 5,106,362 is disclosed in U.S. Pat. No. 5,056,510 also to Gilman. The '510 patent discloses a vented dressing where the fabric reservoir for wound exudate is contained within a chamber. The walls of the chamber are intended to provide a barrier to bacteria and other contaminants. The walls of the chamber are intended to be air permeable so as to permit egress of air from the voids of the fabric reservoir.
U.S. Pat No. 4,909,243 to Frank which is owned by the assignee of the present invention discloses a two piece wound dressing comprising a baseplate having an adhesive surface for contacting surrounding skin. The baseplate has an aperture extending completely through the baseplate and around the wound over which a wound pad of a desired wound dressing material can be placed. This patent provides an aperture that permits visualization of the wound but does not permit reapplication of the dressing over the wound.
Although the prior art wound dressings provide a tortuous path for exudate to an absorbent material, there is a need for a wound dressing that not only provides superior exudate absorption but also a dressing that permits access to, as well as visual inspection of the wound.